Your search for "Black Magic Ritual STP6-EN024" revealed the following:
Black Magic Ritual - STP6-EN024 - Common from Speed Duel Tournament Pack 6, available at 401 Games Canada. Rarity: Common Card Text:This card is used to Ritual Summon "Magician of Black Chaos". You must also Tribute monsters from your hand...
Magician of Black Chaos - STP6-EN023 - Common from Speed Duel Tournament Pack 6, available at 401 Games Canada. Rarity: Common Card Text:You can Ritual Summon this card with "Black Magic Ritual".Official Tournament Stores must review their Konami OTS agreement...